1. Field of the Invention
The present invention relates to an apparatus for aligning a dispenser, a method of aligning a dispenser, and a dispenser alignment system, and more particularly, to an apparatus for aligning a liquid crystal dispenser, a method of aligning a liquid crystal dispenser, and a dispenser alignment system.
2. Description of the Related Art
In general, liquid crystal display (LCD) devices display images based upon data signals that are supplied to individual liquid crystal cells arranged in a matrix configuration. Accordingly, light transmittance of each of the individual liquid crystal cells is controlled to display the images.
The LCD devices commonly include a liquid crystal display panel having pixels arranged in a matrix configuration and a driving circuit for driving the pixels. The liquid crystal display panel includes a color filter (CF) substrate and a thin film transistor (TFT) array substrate attached together to face each other using a seal pattern formed along outer edge portions of an effective image display part. Accordingly, spacers are formed on either the TFT array substrate or the CF substrate to provide a uniform cell gap between the attached CF and TFT array substrates, and a liquid crystal layer is positioned between the CF and TFT array substrates within the cell gap. In addition, a polarization plate and a phase difference plate are provided at an outer surface of the TFT array substrate and the CF substrate. Thus, by selectively changing a light transmission state or a light refractivity state, the LCD device can have high luminance and contrast characteristics.
In the liquid crystal display panel, a common electrode and a pixel electrode are formed to induce an electric field to the liquid crystal layer. For example, when a voltage is supplied to the common electrode and a voltage supplied to the pixel electrode is controlled, individual light transmittance of unit pixels are controlled. In order to control the voltage supplied to the pixel electrode by the unit pixels, a TFT is commonly used as a switching unit that is formed at each of the unit pixels. In addition, alignment layers are formed at both facing surfaces of the TFT array substrate and the CF substrate, and the alignment layers are rubbed to provide an initial alignment direction of liquid crystals of the liquid crystal layer.
Elements of the liquid crystal display device will now be described with reference to the accompanying drawings.
FIG. 1 is a plan view of a unit liquid crystal display panel according to the related art. In FIG. 1, a unit liquid crystal display panel is formed by a TFT array substrate and a CF substrate. As shown in FIG. 1, a liquid crystal display panel 100 includes an image display part 113 where the liquid crystal cells are arranged in a matrix configuration, a gate pad part 114 connected to gate lines of the image display part 113, and a data pad part 115 connected to data lines. The gate pad part 114 and the data pad part 115 are formed along edge regions of the TFT array substrate 101 that do not overlap with the CF substrate 102. The gate pad part 114 supplies scan signals from a gate driver integrated circuit (IC) (not shown) to the gate lines of the image display part 113, and the data pad part 115 supplies data signals from a data driver IC (not shown) to the data lines of the image display part 113.
The data lines and the gate lines are provided on the TFT array substrate 101 of the image display part 113 to intersect each other. In addition, a TFT is provided at each intersection of the data and gate lines for switching a corresponding one of the liquid crystal cells. Moreover, a pixel electrode is provided on the TFT array substrate 101 for driving each of the liquid crystal cells connected to a corresponding one of the TFTs, and a passivation film is formed along an entire surface of the TFT array substrate 101 for protecting the TFTs.
Although not shown, the CF substrate 102 includes color filters provided within the liquid crystal cells and are separated by a black matrix. In addition, a transparent common electrode (not shown) is provided on the CF substrate 102 of the image display part 113. Furthermore, the TFT array substrate 101 and the CF substrate 102 are attached together using a seal pattern 116 formed along outer edge portions of the image display part 113, and spacers (not shown) are provided between the TFT array substrate 101 and the CF substrate 102 to form a uniform cell gap.
During fabrication of the liquid crystal display panel, simultaneous formation of a plurality of individual liquid crystal display panels on a large-scale mother substrate is commonly performed. Accordingly, a process for separating the individual liquid crystal display panels from the large-scale mother substrate is required, wherein cutting and processing of the mother substrate is performed. Then, after each of the individual liquid crystal display panels is separated from the large-scale mother substrate, liquid crystal material is injected through a liquid crystal injection port 118 formed in the seal pattern 116 to form a liquid crystal layer within the cell gap that is formed between the TFT array substrate 101 and the CF substrate 102. Next, the liquid crystal injection port 118 is sealed.
According to the fabrication of the liquid crystal display panel, the TFT array substrate 101 and the CF substrate 102 are separately fabricated on individual first and second mother substrates that are attached together to include a uniform cell gap therebetween. Next, the attached first and second mother substrates are cut into individual unit panels, and the liquid crystal material is injected into the cell gap between the TFT array substrate 101 and the CF substrate 102. Then, a process of forming the seal pattern 116 along the outer edges of the image display part 113 is required to attach the TFT array substrate 101 and the CF substrate 102 together.
FIG. 2A is schematic plan view of an apparatus for printing a seal pattern according to the related art, and FIG. 2B is a schematic cross sectional view of the apparatus of FIG. 2A according to the related art. In FIGS. 2A and 2B, a patterned screen mask 206 is provided onto a substrate 200 having a plurality of seal pattern regions 216A˜216F, wherein the substrate 200 may be one of the TFT substrate 101 (in FIG. 1) or the CF substrate 102 (in FIG. 1). Then, a rubber squeegee 208 is provided for selectively supplying sealant material 203 to exposed portions of the substrate 200 through the patterned screen mask 206. Accordingly, a plurality of seal patterns 216A˜216F are simultaneously formed along each outer edge portion of image display parts 213A˜213F of the substrate 200, and liquid crystal injection openings 204A˜204F are formed at one side of each of the seal patterns 216A˜216F for injecting liquid crystal material into a gap to be formed between the TFT array substrate 101 (in FIG. 1) and the CF substrate 102 (in FIG. 1). Thus, the seal patterns 216A˜216F formed on the substrate 200 confine the liquid crystal material and prevent leakage of the liquid crystal material.
A method of screen printing the seal patterns 216A˜216F includes applying the sealant 203 onto the patterned screen mask 206, forming the seal patterns 216A˜216F on the substrate 200 using the rubber squeegee 208, and drying the seal pattern 216A˜216F by evaporating solvent contained in the sealant material 203 and leveling the sealant material 203. Although the screen printing method is commonly used because of its simplicity, the method results in significant amounts of sealant material waste. Specifically, large amounts of the sealant material is wasted since it is applied along an entire surface of the patterned screen mask 206 in order to simultaneously form the seal patterns 216A˜216F using the rubber squeegee 208. Accordingly, any excess sealant material that is printed through the plurality of seal pattern regions 216A˜216F of the patterned screen mask 206 is discarded.
In addition, the screen printing method is disadvantageous in that a rubbed alignment layer (not shown) formed on the substrate 200 is degraded as a result of the patterned screen mask 206 being brought into contact with the substrate 200. Accordingly, the degradation of the rubbed alignment layer corrupts picture quality of the LCD device. Thus, a seal dispensing method has been developed.
FIG. 3 is a schematic plan view of method of dispensing a seal pattern according to the related art. In FIG. 3, as a substrate 300 loaded onto a table 310 is moved X- and Y-directions, a plurality of seal patterns 316A˜316F are formed along outer edge portions of each image display part 313A˜313F formed on the substrate 300 by applying pressure to a plurality of syringes 301A˜301C filled with sealant material. Accordingly, a first column group of the seal patterns 316A˜316C are simultaneously formed along outer edge portions of the image display parts 313A-313C, and then a second column group of the seal patterns 316D-316F are simultaneously formed along outer edge portions of the image display parts 313D-313F. Thus, sealant material waste may be reduced. In addition, since the syringes 301A˜301C do not contact the rubbed alignment layer (not shown), damage to the rubbed alignment layer is prevented and picture quality of the LCD device is not corrupted. However, the syringes 301A˜301C must be precisely aligned with the substrate 300 to accurately form the seal patterns 316A˜316F at desired positions. For example, if the syringes 301A˜301C are not properly aligned with the substrate 300, the seal patterns 316A˜316F formed on the substrate 300 can be formed within the image display parts 313A˜313F, rather than along the outer edge portions of the image display parts 313A˜313F. Accordingly, the liquid crystal display panel may be defective.
FIGS. 4A to 4F are sequential schematic perspective views of a dispenser alignment method according to the related art. In FIG. 4A, a dummy substrate 411 is loaded onto a table 410.
In FIG. 4B, the table 410 is moved to a predetermined position, and sealant material is discharged onto the dummy substrate 411 through a syringe 401A to form a first cross alignment pattern 412. Then, an image of the first cross alignment pattern 412 is detected using a first image camera 402A provided at a side of the syringe 401A, and the image is displayed using a display unit 420. The display unit 420 simultaneously displays a position of the first alignment pattern 412 and a first reference position.
In FIG. 4C, the table 410 is moved in X- and Y-directions so that the position of the first alignment pattern 412 displayed on the display unit 420 and the first reference position can be aligned to correspond to each other.
In FIG. 4D, after the table 410 is moved to a predetermined different position, the sealant material is discharged onto the dummy substrate 411 through the syringe 401A to form a second cross alignment pattern 413.
In FIG. 4E, the image of the second alignment pattern 413 is detected using a second image camera 402B, and is displayed using the display unit 420. In addition, the display unit 420 simultaneously displays the position of the second alignment pattern 413 and a second reference position.
In FIG. 4F, the second image camera 402B is moved along X- and Y-directions so that the position of the second alignment pattern 413 displayed on the display unit 420 and the second reference position can be aligned to correspond to each other. Then, after the dispenser is aligned using the dummy substrate 411, the dummy substrate 411 is unloaded from the table 410, and a substrate having a plurality of image display parts (not shown) formed thereon is loaded onto the table 410. Next, seal patterns are formed along each outer edge portion of the image display parts through a plurality of syringes (not shown).
In FIGS. 4A-4F, when sealant material filled in the plurality of syringes (not shown) decreases to an amount that further seal patterns may not be formed, the syringe or syringes must be replaced with new syringes filled with sealant material. Accordingly, since an alignment state between the dispenser and the table 410 is compromised due to replacement of the syringe(s), the dispenser alignment process, as shown in FIGS. 4A to 4F, must be repeated. In addition, if a defective seal pattern is detected during a follow-up testing process, the syringe(s) may be replaced and the dispenser alignment process, as shown in FIGS. 4A to 4F, must be repeated. Moreover, anytime the syringe(s) are moved or replaced, the dispenser alignment process, as shown in FIGS. 4A to 4F, must be repeated.
As sizes of the liquid crystal display panels are increased, an area of the substrate for fabricating large-scale liquid crystal display panels also increases. Accordingly, since the dummy substrate 411 used for aligning the dispenser must be substantially the same size as the substrate for fabricating the liquid crystal display panels, the size of the dummy substrate 411 must be increased. Thus, manual loading and unloading of the dummy substrate 411 increases a processing time for aligning the dispenser, thereby degrading productivity of the LCD device. In addition, since loading and unloading of the large-scale dummy substrate 411 is manually performed, probability of damage to the dummy substrate 411 increases, thereby increasing production costs of the LCD device. Moreover, in order to manually load and unload the large-scale dummy substrate 411, a certain amount of space must be reserved for storage of the large-scale dummy substrate 411. Thus, efficient use of clean room space in which the LCD device is fabricated decreases, thereby increasing facility costs.
In addition, when sealant material filled in the syringe(s) falls below a preset level and is not adequate to form additional seal patterns, the syringe(s) must be replaced with a new syringe. Alternatively, when a defective seal pattern is detected during a follow-up testing process, the dummy substrate must be loaded onto the table to align the dispenser and then unloaded, thereby increasing processing time and reducing productivity.